Integrated circuits are preferably tested in either wafer form or packaged form. When the integrated circuits are in either of these two forms, they are relatively easy to handle. For example, before a wafer is diced into individual integrated circuit chips, the wafer is large and easy to mount and position relative to a test station. Because of the size of the wafer, it is relatively easy to hold the wafer from positions on the wafer that do not physically interfere with either electrically probing or viewing the device under test. Similarly, packaged devices are also relatively easy to test compared to individual devices. Once the individual integrated circuit device is mounted and electrically connected to the packaging, the package is easily mounted and electrically connected to a test station.
However, sometimes it is necessary to test an integrated circuit that is neither in wafer form nor in package form. This need might arise either between the time that the wafer is diced and the individual devices are packaged, or after a device has been removed from its packaging for some reason, such as during failure analysis.
Special problems are encountered when testing individual devices. For example, because of the small size of individual devices, compared to either wafers or packages, they are more difficult to hold. Further, and also because of the small size of individual devices, they tend to be more difficult to hold in a manner that allows the device to be viewed or electrically probed. This problem is compounded when it is important for both the front and back surfaces of the device to be probed or viewed during testing. Further, individual devices tend to be far more fragile than packaged devices, and thus they are more easily damaged during testing than are packaged devices.
What is needed, therefore, is a fixture that allows an individual integrated circuit device to be safely held such that both surfaces of the integrated circuit can be probed, viewed, or both.